This change introduces a new resume token format (v2). Both 6.0 and 7.0 servers can understand the v1 and v2 format. If there are any internal teams that decode the resume token, they might be impacted.

Description of Linked Ticket

After 6.0, we should start generating the new, standardised token format for all events. This will require us to set the default token version to 2, to make $_generateV2ResumeTokens an optional parameter, and to have mongoS and mongoD assume that its value is true unless it is present and explicitly false. This ticket should also include upgrade/downgrade work to ensure that a change stream can survive upgrades between 6.0 and later releases.